1. Field of the Invention
The invention relates to surprisingly effective antimicrobial compositions suitable for use in the protection of paints, paint films, wood, wood composite products, leather, metal working fluids, mineral slurries, inks, dispersions and other products.
2. Background of the Invention
Materials which can be degraded by microorganisms such as fungi, yeast, bacteria and algae include, for example, coatings, surfactants, proteins, inks, emulsions, resins, stuccoes, concretes, stones, woods (including wood-plastic composites), adhesives, caulks, sealants, and leathers. Aqueous latex paints; polymer dispersions containing polyvinyl alcohol, polyacrylates or vinylpolymers; thickener solutions containing cellulose derivatives, clay and mineral suspensions; and metal working fluids are also prone to degradation by the action of microorganisms. The degradation may produce, among other things, discoloration, odors, changes in pH values, and/or changes in rheological properties.
Generally, a composition in a smaller amount that provides the same antimicrobial activity is a superior product, as compared to other antimicrobial compositions. Ideally, these superior compositions should protect against a wide variety of problem microorganisms and remain effective for an extended period of time, without adversely affecting the product to be protected, the health of people who make or use the product, or the environment.
One approach to formulating compositions that require a smaller amount to provide the same antimicrobial activity is to employ biologically active ingredients which exhibit a synergistic effect when acting together. For example, U.S. Pat. No. 6,197,805, issued to Roger Errol Smith and assigned to the assignee of the present application, teaches that when 3-iodo-2-propynyl butyl carbamate and 2-(methoxycarbonylamino)benzimidazole are combined as active ingredients in a ratio which is greater than about 2 parts of the benzimidazole to about 1 part of the iodopropynyl compound, they form antimicrobial compositions which can exhibit synergy between the two active ingredients. U.S. Pat. No. 6,197,805 is hereby incorporated in its entirety, and particularly for its teachings regarding the use of 3-iodo-2-propynyl butyl carbamate and 2-(methoxycarbonylamino)benzimidazole as antimicrobial ingredients.
U.S. Pat. No. 6,416,789, issued to Brian Marks et al., describes a wood treatment material containing a synergistic combination of fungicides. The combination of the '789 patent is said to include boron-containing compounds such as zinc borate, organo-iodine compounds such as 3-iodo-2-propynyl butyl carbamate, and amine-oxides such as N-alkyl-N,N-dimethylamine oxide. The '789 patent reports that wood treated with the combination resists decay, mold and mildew. The '789 patent is silent regarding the use of 2-(methoxycarbonylamino)benzimidazole as a synergistic active ingredient.
U.S. Pat. No. 6,884,811, issued to Kazuhide Fujimoto, describes an industrial antifungal composition comprising synergistically effective amounts of iodo-2-propynyl butyl carbamate, 2-(methoxycarbonylamino)benzimidazole, and 4,5-dichloro-2-octyl-isothiazolin-3-one. The '805 patent reports that the composition is particularly useful when applied to wood and to paint. However, isothiazolin-3-ones are known to act as chemical sensitizers under some conditions. For this and other reasons, alternatives to the antifungal composition of the '811 are still needed.
Borates have long been used as broad-spectrum wood preservatives. They are effective against many types of fungi, termites and wood-boring beetles, and exhibit low acute mammalian toxicity and low environmental impact. Soluble borates such as boric acid, borax and disodium octaborate tetrahydrate are known as aqueous-based preservative systems for treating solid wood products for use in protected environments, such as interior building applications and painted external joinery. However, because they are readily leached from treated wood when exposed to moisture, soluble borates are not generally suitable for exterior or ground contact applications. Water-insoluble borate compounds which have been used as wood preservatives include zinc borate, calcium silicate borate, sodium silicate borate, aluminum silicate borate, hydroboracite, aluminum borate, copper borate, magnesium borate, and iron borate.
No single organic antimicrobial compound can provide protection against all microorganisms or is suitable for all applications. Chemical stability, toxicological profile, regulatory considerations, environmental concerns, physical properties or other characteristics may render a particular ingredient unsuitable for a particular use. Accordingly, there is a need to constantly develop new antimicrobial compositions that offer broad spectrum protection for a variety of needs.